How was Ali ibn Abi Talib killed? Did he burn anyone? What were the conflicts during his reign? And why did he move the caliphate to Kufa?

Towards the end of his caliphate, matters became turbulent for Ali (may Allah be pleased with him); his army abandoned him, and the power of the people of Sham grew. Then, three Kharijites—Abd al-Rahman ibn Muljam, al-Barak ibn Abdullah al-Tamimi, and Amr ibn Bakr al-Tamimi—convened and conspired to assassinate Ali, Muawiya, and Amr ibn al-Aas. Ibn Muljam killed Ali (may Allah be pleased with him) when he went out for the Fajr prayer, striking him with a poisoned sword. Ali (may Allah be pleased with him) died from his wounds, having enjoined piety towards Allah, prayer, zakat, forgiveness of sins, suppressing anger, maintaining kinship ties, forbearance towards the ignorant, seeking understanding in religion, being steadfast in matters, committing to the Qur'an, good neighborliness, enjoining good and forbidding evil, and avoiding immoral acts.

As for Ali (may Allah be pleased with him) burning some people, he burned the apostates who believed in his divinity. Ibn Abbas disapproved of this, citing the Prophet's (peace and blessings of Allah be upon him) saying, "Do not punish with the punishment of Allah." Ibn Abbas believed that apostates should be killed, not burned.

The reason for the conflict during Ali's (may Allah be pleased with him) caliphate was the assassination of Uthman (may Allah be pleased with him). A group of companions demanded retribution for his killers, while Ali believed in delaying this until affairs stabilized for him. This led to disagreement. Ali (may Allah be pleased with him) moved from Medina to Kufa after realizing that Medina no longer possessed sufficient resources, intending to be closer to the people of Sham who had rebelled against his authority.